(i) Technical Field
The present invention relates to focal plane shutters and optical devices.
(ii) Related Art
A focal plane shutter installed in a camera can be arranged near an image pickup element in consideration of a reduction in thickness of the camera itself. In this case, when a blade of the focal plane shutter closes an opening and stops, the blade might be bent toward the image pickup element side to come into contact therewith. Thus, the image pickup element might be damaged. In Japanese Patent Unexamined Application Publication No. 2006-208980, in consideration of such a problem, the blade includes a first blade and a second blade in an order decreasing movable amounts, and the second blade has rigidity higher than that of the first blade.
However, in a case where the blade includes plural blades having different rigidities, the whole weight of the shutter might increase depending on a material of the second blade. This might influence a shutter speed. Also, in a case where the first blade is made of synthetic resin and the second blade is made of metal, the second blade might cut the first blade to make dust.
Further, in a case where both the first and second blades are made of synthetic resin, the second blade might not ensure the high rigidity. For example, in a case where the shutter speed is high, when the blade closes the opening and stops, a large impact is applied to the blade. Furthermore, for example, in a case where the image pickup element and the focal plane shutter are large, in response to this, the blade is also large. Thus, when the blade closes the opening and stops, the large impact is applied to the shutter. Therefore, when the large impact is applied to the blade, it might be difficult to suppress the bending of the blade including the first and second blades made of synthetic resin.